The malfunctioning of protein kinases (PKs) is the hallmark of numerous diseases. A large share of the oncogenes and proto-oncogenes involved in human cancers code for PKs. The enhanced activities of PKs are also implicated in many non-malignant diseases, such as benign prostate hyperplasia, familial adenomatosis, polyposis, neuro-fibromatosis, psoriasis, vascular smooth cell proliferation associated with atherosclerosis, pulmonary fibrosis, arthritis glomerulonephritis and post-surgical stenosis and restenosis. PKs are also implicated in inflammatory conditions and in the multiplication of viruses and parasites. PKs may also play a major role in the pathogenesis and development of neurodegenerative disorders.
For a general reference to PKs malfunctioning or disregulation see, for instance, Current Opinion in Chemical Biology 1999, 3, 459-465.
PIM-1 is the protooncogene activated by murine leucemia virus (Provirus Integration site for Moloney murine leucemia virus—MoMuLV) that induces T-cell lymphoma [Cuypers, H. T., et. al. Cell, 1984, 37, 141-150].
The expression of the protooncogene produces a non-transmembrane serine/threonine kinase of 313 residues, including a kinase domain consisting of 253 amino acid residues. Two isoforms are known through alternative initiation (p44 and p33) [Saris, C. J. M. et al. EMBO J. 1991, 10, 655-664].
PIM-1, PIM-2 and PIM-3 phosphorylate protein substrates that are important in cancer neogenesis and progression. For example, PIM-1 phosphorylates inter alia p21, Bad, c-myb, Cdc 25A and eIF4B (see e.g. Quian, K. C. et al, J. Biol. Chem. 2005, 280(7), 6130-6137, and references cited therein).
Two PIM-1 homologs have been described [Baytel, D. Biochem. Biophys. Acta 1998, 1442, 274-285; Feldman, J. et al. J. Biol. Chem. 1998, 273, 16535.16543]. PIM-2 and PIM-3 are respectively 58% and 69% identical to PIM-1 at the amino acid level. PIM-1 is mainly expressed in thymus, testis, and cells of the hematopoietic system [Mikkers, H.; Nawijn, M.; Allen, J.; Brouwers, C.; Verhoeven, E.; Jonkers, J.; Berns, Mol. Cell. Biol. 2004, 24, 6104; Bachmann, M.; Moroy, T. Int. J. Biochem. Cell Biol. 2005, 37, 726-730. 6115]. PIM-1 expression is directly induced by STAT (Signal Transducers and Activators of Transcription) transcription factors, and PIM-1 expression is induced by many cytokine signalling pathways such as interleukins (IL), granulocyte-macrophage colony stimulating factor (GM-CSF), α- and γ-interferon, erythropoietin, and prolactin [Wang, Z et al. J. Vet. Sci. 2001, 2, 167-179].
PIM-1 has been implicated in lymphoma development. Induced expression of PIM-1 and the protooncogene c-myc synergise to increase the incidence of lymphomagenesis [Breuer, M. et al. Nature 1989, 340, 61-63; van Lohuizen M. et al. Cell, 1991, 65, 737-752]. PIM-1 functions in cytokine signalling pathways and has been shown to play a role in T cell development [Schmidt, T. et al. EMBO J. 1998, 17, 5349-5359; Jacobs, H. et al. JEM 1999, 190, 1059-1068]. Signalling through gp130, a subunit common to receptors of the IL-6 cytokine family, activates the transcription factor STAT3 and can lead to the proliferation of hematopoietic cells [Hirano, T. et al. Oncogene 2000, 19, 2548-2556]. A kinase-active PIM-1 appears to be essential for the gp130-mediated STAT3 proliferation signal. In cooperation with the c-myc PIM-1 can promote STAT3-mediated cell cycle progression and antiapoptosis [Shirogane, T. et sl., immunity, 1999, 11, 709-719]. PIM-1 also appears to be necessary for IL-3-stimulated growth in bone marrow-derived mast cells [Domen, J. et al., Blood, 1993, 82, 1445-1452] and survival of FDCP1 cells after IL-3 withdrawal [Lilly, M. et al., Oncogene, 1999, 18, 4022-4031].
Additionally, control of cell proliferation and survival by PIM-1 may be effected by means of its phosphorylation of the well-established cell cycle regulators cdc25 [Mochizuki, T. et al., J. Biol. Chem. 1999, 274, 18659-18666] and/or p21(Cip1/WAF1) [Wang Z. et al. Biochim. Biophys. Acta 2002, 1593, 45-55] or phosphorylation of heterochromatin protein 1, a molecule involved in chromatin structure and transcriptional regulation [Koike, N. et al, FEBS Lett. 2000, 467, 17-21].
Mice deficient for all three PIM genes showed an impaired response to hematopoietic growth factors and demonstrated that PIM proteins are required for efficient proliferation of peripheral T lymphocytes. In particular, it was shown that PIM function is required for efficient cell cycle induction of T cells in response to synergistic T-cell receptor and IL-2 signalling. A large number of interaction partners and substrates of PIM-1 have been identified, suggesting a pivotal role for PIM-1 in cell cycle control, proliferation, as well as in cell survival.
The oncogenic potential of this kinase has been first demonstrated in E μ PIM-1 transgenic mice in which PIM-1 over-expression is targeted to the B-cell lineage which leads to formation of B-cell tumors [van Lohuizen, M. et al.; Cell 1989, 56, 673-682. Subsequently PIM-1 has been reported to be over-expressed in a number of prostate cancers, erythroleukemias, and several other types of human leukemias [Roh, M. et al.; Cancer Res. 2003, 63, 8079-8084; Valdman, A. et al; Prostate 2004, 60, 367-371.
For example, chromosomal translocation of PIM-1 leads to overexpression of PIM-1 in diffuse large cell lymphoma. [Akasaka, H. et al.; Cancer Res. 2000, 60, 2335-2341]. Furthermore, a number of missense mutations in PIM-1 have been reported in lymphomas of the nervous system and AIDS-induced non-Hodgkins' lymphomas that probably affect PIM-1 kinase activity or stability [Pasqualucci, L. et al, Nature 2001, 412, 341-346; Montesinos-Rongen, M. et al., Blood 2004, 103, 1869-1875; Gaidano, G. et al., Blood 2003, 102, 1833-184]. Thus, the strong linkage between reported overexpression data and the occurrence of PIM-1 mutations in cancer suggests a dominant role of PIM-1 in tumorigenesis.
Several other protein kinases have been described in the literature, in which the activity and/or elevated activity of such protein kinases have been implicated in diseases such as cancer, in a similar manner to PIM-1, PIM-2 and PIM-3. Such protein kinases include PI3-K, CDK-2, SRC and GSK-3.
There is a constant need to provide alternative and/or more efficacious inhibitors of protein kinases, and particularly inhibitors of CDK-2, SRC, GSK-3, PI3-K, PIM-1, PIM-2 and/or PIM-3. Such modulators are expected to offer alternative and/or improved approaches for the management of medical conditions associated with activity and/or elevated activity of CDK-2, SRC, GSK-3, PI3-K, PIM-1, PIM-2 and/or PIM-3 protein kinases
The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.
International patent application WO 2007/064797 discloses various compounds that may be useful in the treatment of cancer. However, there is no mention in that document of imidazothiadiazoles.
US patent applications US 2007/0049591 and US 2007/0093490 and international patent application WO 2004/058769 all disclose various compounds that may be useful as kinase inhibitors. Further, international patent application WO 2007/0136736 discloses various compounds that may be useful as Lck inhibitors. However, all these documents only mention compounds in which the core ring structure is a 6,5-ring system.
International patent application WO 2004/111060 discloses various imidazothiadiazoles that may be useful in the treatment of neurodegenerative diseases and cancer. However, this document primarily relates to 6-aryl substituted imidazo[2,1-b]-1,3,4-thiadiazoles, substituted in the 2-position with a sulfur (or oxidised derivative thereof) linker group. Further, international patent application WO 03/051890 also discloses various imidazothiadiazoles, which may be useful in the treatment of neurodegenerative diseases and cancer. However, this document primarily relates to 6-aryl substituted imidazo[2,1-b]-1,3,4-thiadiazoles, substituted in the 2-position with a sulfonamide group.
Journal article European Journal of Medicinal Chemistry (2003), 38(7-8), 781-786 by Terzioglu et al discloses various compounds that may be useful in the treatment of cancer. However, this document only discloses compounds that contain a carbohydrazide moiety.
Italian journal article Arzneimittel-Forschung (2000), 50(6), 550-553 by Andreani et al discloses various compounds including specific imidazothiadiazoles. However, there is no mention in this journal article that the compounds disclosed therein may be useful as protein kinase inhibitors.
International patent application WO 97/11075 discloses various compounds imidazothiadiazoles as herbicides. However, there is no disclosure that such compounds may be useful as pharmaceuticals, e.g. in the treatment of cancer.
European patent application EP 662 477 and journal article Journal of the Indian Chemical Society (1979), 56(7), 716-17 by Joshi et al, both disclose various heterobicyclic compounds, including specific imidazolothiadiazole compounds, which may be active as fungicides. However, there is no disclosure in either of these documents that the compounds disclosed therein may be useful as protein kinase inhibitors.
Italian journal article Farmaco, Edizione Scientifica (1985), 40(3), 190-9 by Abignente et al and European patent application EP 41215 both disclose various imidazolothiadiazoles, which may have been tested for medicinal properties for research purposes.
Various imidazolothiadiazoles have also been disclosed in Journal of the Indian Chemical Society (1982), 59(10), 1170-3 as potential fungicides and/or bactericides.
Various other imidazolothiadiazoles have also been disclosed in the CAS registry database, but to which compounds no use has apparently been ascribed.